Submission #448674

#	Time	Username	Problem	Language	Result	Execution time	Memory
448674		vanic	The Forest of Fangorn (CEOI14_fangorn)	C++14	100 / 100	667 ms	1196 KiB

fangorn

#include <cstdio>
#include <cmath>
#include <algorithm>
#include <vector>

using namespace std;

const int maxn=2005, maxm=1e4+5;
const double inf=2e18;

pair < int, int > d[maxn];
pair < int, int > q[maxm];
int n, m;

vector < double > kor[4]; // jednadzbe: x=0, y=0, x=w, y=h
vector < pair < double, int > > sw[4];
bool moze[maxm];
vector < int > sol;
pair < int, int > pos;
int w, h;

void radi(int x, int y){
	double a, b, c;
	int dx, dy;
	dx=d[x].first-d[y].first;
	dy=d[x].second-d[y].second;
	a=-dy;
	b=dx;
	c=-a*d[x].first-b*d[x].second;
	double sol1, sol2, sol3, sol4;
	if(b==0){
		sol1=-inf;
		sol3=inf;
	}
	else{
		sol1=-c/b;
		sol3=(-c-a*w)/b;
	}
	if(a==0){
		sol2=-inf;
		sol4=inf;
	}
	else{
		sol2=-c/a;
		sol4=(-c-b*h)/a;
	}
	if(b==0){
		if(d[x].second<d[y].second){
			kor[0].push_back(sol1);
			kor[2].push_back(sol1);
		}
		else{
			kor[0].push_back(sol3);
			kor[2].push_back(sol3);
		}
	}
	else if(d[x].first<d[y].first){
		kor[0].push_back(sol1);
	}
	else{
		kor[2].push_back(sol3);
	}
	if(a==0){
		if(d[x].first<d[y].first){
			kor[1].push_back(sol2);
			kor[3].push_back(sol2);
		}
		else{
			kor[1].push_back(sol4);
			kor[3].push_back(sol4);
		}
	}
	else if(d[x].second<d[y].second){
		kor[1].push_back(sol2);
	}
	else{
		kor[3].push_back(sol4);
	}
}

double ccw(pair < double, double > a, pair < double, double > b, pair < double, double > c){
	return a.first*(b.second-c.second)+b.first*(c.second-a.second)+c.first*(a.second-b.second);
}

bool provjeri(pair < double, double > a, pair < double, double > b, pair < double, double > c, pair < double, double > x){
	if(ccw(a, b, c)<0){
		swap(b, c);
	}
	return ccw(a, b, x)>=0 && ccw(b, c, x)>=0 && ccw(c, a, x)>=0;
}

void rijesi(int x, int y){
	sort(kor[y].begin(), kor[y].end());
	pair < double, double > t1, t2;
	if(y==0){
		t1.first=0;
		t2.first=0;
	}
	else if(y==1){
		t1.second=0;
		t2.second=0;
	}
	else if(y==2){
		t1.first=w;
		t2.first=w;
	}
	else{
		t1.second=h;
		t2.second=h;
	}
	int ind=-1;
	for(int i=0; i<(int)kor[y].size()-1; i++){
		if(y==0){
			t1.second=kor[y][i];
			t2.second=kor[y][i+1];
		}
		else if(y==1){
			t1.first=kor[y][i];
			t2.first=kor[y][i+1];
		}
		else if(y==2){
			t1.second=kor[y][i];
			t2.second=kor[y][i+1];
		}
		else{
			t1.first=kor[y][i];
			t2.first=kor[y][i+1];
		}
		if(provjeri(t1, t2, d[x], pos)){
			ind=i;
			break;
		}
	}
	if(kor[y].size()>1){
		sw[y].push_back({kor[y][0], 1});
		sw[y].push_back({kor[y].back(), -1});
		if(ind!=-1){
			for(int i=0; i<m; i++){
				if(moze[i] && !provjeri(t1, t2, d[x], q[i])){
					moze[i]=0;
				}
			}
			sw[y].push_back({kor[y][ind], -1});
			sw[y].push_back({kor[y][ind+1], 1});
		}
	}
}

int main(){
	scanf("%d%d", &w, &h);
	scanf("%d%d", &pos.first, &pos.second);
	scanf("%d", &m);
	for(int i=0; i<m; i++){
		moze[i]=1;
		scanf("%d%d", &q[i].first, &q[i].second);
	}
	scanf("%d", &n);
	for(int i=0; i<n; i++){
		scanf("%d%d", &d[i].first, &d[i].second);
	}
	for(int i=0; i<n; i++){
		for(int j=0; j<n; j++){
			if(i==j){
				continue;
			}
			radi(i, j);
		}
		for(int j=0; j<4; j++){
			rijesi(i, j);
			kor[j].clear();
		}
	}
	for(int i=0; i<m; i++){
		if(q[i].first==0){
			sw[0].push_back({q[i].second, i+2});
		}
		else if(q[i].second==0){
			sw[1].push_back({q[i].first, i+2});
		}
		else if(q[i].first==w){
			sw[2].push_back({q[i].second, i+2});
		}
		else{
			sw[3].push_back({q[i].first, i+2});
		}
	}
	int val;
	for(int i=0; i<4; i++){
		sort(sw[i].begin(), sw[i].end());
		val=0;
		for(int j=0; j<(int)sw[i].size(); j++){
			if(sw[i][j].second<2){
				val+=sw[i][j].second;
			}
			else{
				if(val || !moze[sw[i][j].second-2]){
					continue;
				}
				sol.push_back(sw[i][j].second-1);
			}
		}
	}
	printf("%d\n", (int)sol.size());
	sort(sol.begin(), sol.end());
	for(int i=0; i<(int)sol.size(); i++){
		printf("%d ", sol[i]);
	}
	printf("\n");
	return 0;
}

Compilation message (stderr)

fangorn.cpp: In function 'int main()':
fangorn.cpp:150:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  150 |  scanf("%d%d", &w, &h);
      |  ~~~~~^~~~~~~~~~~~~~~~
fangorn.cpp:151:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  151 |  scanf("%d%d", &pos.first, &pos.second);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fangorn.cpp:152:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  152 |  scanf("%d", &m);
      |  ~~~~~^~~~~~~~~~
fangorn.cpp:155:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  155 |   scanf("%d%d", &q[i].first, &q[i].second);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fangorn.cpp:157:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  157 |  scanf("%d", &n);
      |  ~~~~~^~~~~~~~~~
fangorn.cpp:159:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  159 |   scanf("%d%d", &d[i].first, &d[i].second);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 30 / 30
• Subtask 2: 20 / 20
• Subtask 3: 30 / 30
• Subtask 4: 20 / 20